Add 4x4 downsample filter with 4 bilinear texture reads, use for ssaa.

Review URL: http://codereview.appspot.com/4483042/

git-svn-id: http://skia.googlecode.com/svn/trunk@1250 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/GrGpuGLFixed.cpp b/gpu/src/GrGpuGLFixed.cpp
index 4440bcd..dbfac43 100644
--- a/gpu/src/GrGpuGLFixed.cpp
+++ b/gpu/src/GrGpuGLFixed.cpp
@@ -56,6 +56,7 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 GrGpuGLFixed::GrGpuGLFixed() {
+    f4X4DownsampleFilterSupport = false;
 }
 
 GrGpuGLFixed::~GrGpuGLFixed() {